Electro-optic materials exhibit optical properties that can be altered by application of an electric field, current, or other electromagnetic fields. The most common of these materials are liquid crystals, electrochromic, and Kerr materials. Changes in the absorption properties of these materials can be utilized to make electronically controllable devices such as electronically controllable eyewear, goggles, visors, and welding masks. An example of these devices are the E-TINT® (liquid crystal device (LCD) with electronically controlled tint) based ski goggles sold by the sporting goods manufacturer UVEX® and its affiliates or autodimming filters sold for welding helmets. In the ski goggle product, a switch is used to change the state of the system from clear to dark in the energized state and from dark to clear in the unenergized state. For welding helmets, there is a photosensitive cell, such as a photodiode, photoresistor, solar cell, etc. (collectively named photosensor), which causes application of a voltage to the device when there is sufficient light from the welding arc to activate the device and induce a state change in the material. Once the arc is off, the device returns to the un-energized state. Therefore, currently, to our knowledge, there are commercial systems that provide either manual or automatic control of the optical device but not both within the same device.
One desired feature of electronically controllable optical devices is to give the user of such devices control over many functions in a simple fashion while the user is still “wearing” the device. For example, it is desirable to give the operator the ability to change the state of the device from clear to dark (or colored) as well as the ability to change other features of the device, e.g. the ability to switch between manual and automatic modes. Other operational modes can also be controlled, such as: the ability during the automatic operation mode to set the level of light that can cause a state change (i.e. the sensitivity of the photosensor to the ambient light level), the ability to change the color if the device has multiple color modes, the ability to adjust the “darkness” level of the device, and/or the ability to return the system to its original factory setting.
The method that is currently used to achieve all these functions is to provide multiple switches on the optical device. This approach, however, is commercially cumbersome and undesired since it introduces bulk, weight, cost, and potential for error. In particular, in some optical applications such as eyewear, there are significant size limitations which can severely hinder the ability to include multiple switches within the eyewear frame. Another problem with multiple switches is operator error if the wrong switch is pressed, especially since in most applications, the switch needs to be operated while the user is wearing the eyewear so the user must rely on a tactile response because the switch is out of eyesight. This is especially important in environments where the operator has only a short response time (e.g. military setting, sports, etc.). Another factor is that the user may only have one free hand and therefore operation of multiple switches can become cumbersome.
Therefore, there is a need in the art for an electronically controllable optical device that has a control apparatus that can provide multiple-function control over the optical device in a “blind” fashion (without the need for the operator to see which switch they are activating). One way to achieve this, as described below, is to create a system in which a single switch is coded to provide multiple functions needed.